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  1. 8 Acta Geophysica
  2. 5 Oceanologia
  3. 4 International Journal of Applied Mechanics and Engineering
  4. 2 Archives of Thermodynamics
  5. 2 Bulletin of the Polish Academy of Sciences. Technical Sciences
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  1. 1 2024
  2. 1 2023
  3. 1 2022
  4. 3 2020
  5. 3 2019
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  1. 5 Massel S. R.
  2. 2 Gabr M.
  3. 2 Gupta K. C.
  4. 2 Klecha T.
  5. 2 Lotfy K.
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1
Content available remote Signal reconstruction of surface waves on SASW measurement using Gaussian Derivative wavelet transform
100%
Rosyidi S. A. P. , Taha M. R. , Chik Z. , Ismail A.
Acta Geophysica
|
2009
|
tom Vol. 57, no. 3
616-635
EN
Surface wave method consists of measurement and processing of the dispersive Rayleigh waves recorded from two or more vertical transducers. The dispersive phase data are inverted and the shear wave velocity versus depth is obtained. However, in case of residual soil, the reliable phase spectrum curve is difficult to be produced. Noises from nature and other human-made sources disturb the generated surface wave data. In this paper, a continuous wavelet transform based on mother wavelet of Gaussian Derivative was used to analyze seismic waves in different frequency and time. Time-frequency wavelet spectrum was employed to localize the interested seismic response spectrum of generated surface waves. It can also distinguish the fundamental mode of the surface wave from the higher modes of reflected body waves. The results presented in this paper showed that the wavelet analysis is able to determine reliable surface wave spectrum of sandy clayey residual soil.
2
Content available Flow-induced Vibrations of a Horizontal Elastic Band Plate Submerged in Fluid of Finite Depth
100%
Szmidt K. , Hedzielski B.
Archives of Hydro-Engineering and Environmental Mechanics
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2019
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tom Vol. 66, nr 3-4
101--130
EN
The paper deals with forced vibrations of a horizontal thin elastic plate submerged in a semi-infinite layer of fluid of constant depth. The pressure load on this plate is induced by water waves arriving at the plate. This load is accompanied by pressure resulting from the motion of the plate. The plate and fluid motions depend on boundary conditions, and, in particular, the pressure load depends on the width of the gap between the plate and the bottom. In theoretical description of the phenomenon, we deal with a coupled problem of hydrodynamics in which the plate and fluid motions are coupled through boundary conditions at the plate surfaces. The main attention is focused on transient solutions of the problem, which correspond to fluid (and plate) motion starting from rest. In formulation of this problem, a linear theory of small deflections of the plate is employed. In order to calculate the fluid pressure, a solution of Laplace’s equation is constructed in a doubly connected fluid domain. With respect to the initial value problem considered, we confine our attention to a finite fluid domain. For a finite elapse of time, measured from the starting point, the solution in the finite fluid area mimics a solution within an infinite domain, inherent for wave propagation problems. Because of the complicated structure of boundary conditions of the coupled problem considered, the fluid domain is divided into sub-domains of simple geometry, and the solutions of the problem equations are constructed separately in each of these domains. Numerical experiments have been conducted to illustrate the formulation developed in this paper.
3
Content available remote Propagation of surface waves in a nonhomogeneous anisotropic elastic semi-space
100%
Klecha T.
Bulletin of the Polish Academy of Sciences. Technical Sciences
|
1998
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tom Vol. 46, nr 2
163-176
EN
In the paper the previous results of the author on the surface waves in a nonhomogeneous isotropic elastic semi-space [4], [6] has been extended to an anisotropic semi-space. It is shown, that the velocity and the amplitude of the surface waves in the non homogeneous anisotropic elastic semi-space, with non homogeneity depending on a semi-space depth, are the analytical functions of the wave number. The branches of the dispersion relation have only algebraic singularities and the singularities are at most countable. Moreover it is demonstrated that for the nonhomogeneous isotropic halfspace with a constant density and a shear modulus, and under the assumption that the Poisson ratio is a bounded function of class C2 [0, [nieskończoność]), there exists at least one solution, and at most finite number of solutions of the dispersion equation.
4
Surface waves in a heterogeneous layer over a liquid saturated poro-elastic solid half space
100%
Pal P.
Acta Geophysica Polonica
|
2000
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tom Vol. 48, nr 2
195-205
EN
Rayleigh waves in a heterogeneous layer over a saturated half space are investigated under plane strain conditions. The dispersion equation is derived using the methods for propagation of free waves in layered media. The effect of heterogeneity on phase velocity is studied by taking different numerical values of heterogeneity factor and the result is shown graphically.
5
Content available remote Analysis of Surface Wave Operator in a Nonhomogeneous Isotropic Elastic Semi-space. Part II
100%
Klecha T.
Bulletin of the Polish Academy of Sciences. Technical Sciences
|
2000
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tom Vol. 48, nr 4
499-504
EN
In the paper (1) an alternative approach to the problem of surface wave propagation in a nonhomogeneous elastic semi-space was presented [formula]. The problem was formulated in terms of the stress tensor components vanishing on the semi-space boundary. The equation [formula] with the boundary conditions [formula] and a compatibility condition for the field beta were analysed. Here [formulas] denotes the normal and tangential components, respectively, of the stress tensor amplitude to the semi-space boundary. In the present paper we demonstrate that a solution of the equation [formula] satisfying the conditions [formula] can be extended to infinity.
6
Obliczenia i pomiary parametrów akustycznych fal powierzchniowych w niobianie litu o orientacji 128° YX
100%
Soluch W. , Łysakowska M.
Elektronika : konstrukcje, technologie, zastosowania
|
2000
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tom Vol. 41, nr 3
18-20
PL
Przedstawiono wyniki obliczeń i pomiarów parametrów akustycznych fal powierzchniowych w niobianie litu (LiNbO3) o orientacji 128° YX, który jest powrzechnie stosowany w produkcji filtrów z akustyczn a falą powierzchniową (AFP). Obliczenia przeprowadzono przy wykorzystaniu opracowanego wczesniej programu komputerowego, który został przystosowany do obliczeń przy uwzględnieniu skończonej grubości warstwy metalu naniesionej na podłoże piezoelektryczne. Do pomiaru parametrów AFP zastosowano metodę czwórniakowego rezonansu synchronicznego. Uzyskano bardzo dobrą zgodność wyników obliczeń i pomiarów,
EN
Results of calculations and measurements of SAW parameters in 128° YX cut lithium niobate, which is used in mass production of surface acoustic wave (SAW) filters, are presented. The calculations were performed by means of a computer program, which was adapted for calculations with finite thickness of a metal layer deposited on a piesoelectric substrate. A two port synchronous resonator method was used for SAW parameters measurements. Very good agreement was obtained between the results of calculations and measurements.
7
Content available remote Surface waves in deep and shallow waters
100%
Massel S. R.
Oceanologia
|
2010
|
tom No. 52 (1)
5-52
EN
The motion of water due to surface waves is the most dynamic factor observed in the marine environment. In this review various aspects of the wave modelling of non-linear, steep surface waves and their role in the atmosphere-ocean interaction are discussed. Significant improvements in wave forecasting have been made in the last ten years. This is to a large extent related to substantial progress in the description of wind forcing and other processes, as well as to the more efficient use of satellite observations and assimilation methods. One striking observation is the increasing variety and complexity of models in which more physical processes are implemented, greater precision and resolution achieved and extended ranges of applicability demonstrated. However in order to evaluate the applicability of particular models, comparison with high quality experimental data, collected in nature or under laboratory conditions, is necessary.
8
Content available remote Surface wave generation due to glacier calving
100%
Massel S. R. , Przyborska A.
Oceanologia
|
2013
|
tom No. 55 (1)
101-127
EN
Coastal glaciers reach the ocean in a spectacular process called "calving". Immediately after calving, the impulsive surface waves are generated, sometimes of large height. These waves are particularly dangerous for vessels sailing close to the glacier fronts. The paper presents a theoretical model of surface wave generation due to glacier calving. To explain the wave generation process, four case studies of ice blocks falling into water are discussed: a cylindrical ice block of small thickness impacting on water, an ice column sliding into water without impact, a large ice block falling on to water with a pressure impulse, and an ice column becoming detached from the glacier wall and falling on to the sea surface. These case studies encompass simplified, selected modes of the glacier calving, which can be treated in a theoretical way. Example calculations illustrate the predicted time series of surface elevations for each mode of glacier calving.
9
Content available remote Experimental study of the formation of steep waves and breakers [commun.]
100%
Massel S. R. , Tęgowski J. , Chomka M. , Wichorowski M. , Dąbrowski J. , Stansberg C. T. , Moe V.
Oceanologia
|
2001
|
tom No. 43 (3)
353-363
EN
Breaking waves (whitecaps) are one of the most important and least understood processes associated with the evolution of the surface gravity wave field in the open sea. This process is the principal means by which energy and momentum are transferred away from a developing sea. However, an estimation of the frequency of breaking waves or the fraction of sea surface covered by whitecaps and the amount of dissipated energy induced by breaking is very difficult to carry out under real sea conditions. A controlled experiment, funded by the European Commission under the Improving Human Potential Access Infrastructures programme, was carried out in the Ocean Basin Laboratory at MARINTEK, Trondheim (Norway). Simulation of random waves of the prescribed spectra by wave makers provided a very realistic pattern of the sea surface. The number of breaking waves was estimated by photographing the sea surface and recording the noise caused by the breaking waves. The experimental data will serve for calibration of the theoretical models of the sea surface fraction related to the whitecaps.
10
Content available remote Circulation of groundwater due to wave set-up on a permeable beach
100%
Massel S. R.
Oceanologia
|
2001
|
tom No. 43 (3)
279-290
EN
Sandy beaches are highly exploited but very dynamic and fragile environments. Driven by waves, the water flow through the beach body is able to transport oxygen, and hence help to maintain biological activity in the porous media. The paper presents a theoretical attempt to predict the groundwater circulation due to wave set-up. Two systems of circulations have been discovered, related to two different gradients of the set-up height. For the offshore gradient, the horizontal excess pressure gradient induces flow in the offshore direction. However, closer to the shore, the pressure gradient is reversed and the resulting flow moves shorewards.
11
Content available Wave propagation in 2D between two elastic media in contact in theory of generalized two temperature thermoelasticity with gravity effect
88%
Lotfy K. , Gabr M. , El-Bary A. A.
Archives of Thermodynamics
|
2020
|
tom Vol. 41, no 1
219--243
EN
The theory of generalized two-temperature thermoelasticity is used to solve the boundary value problems between two elastic media with two different types of temprature under the influence of gravity.The classical dynamical coupled theory and Lord-Şhulman theory are used to obtain the general solution of the governing equations and investigate the effect of surface waves in an isotropic elastic medium subjected to gravity field. The harmonic vibrations method is used to obtain the displacement components, stress tensor and temperature distribution in the considerd physical domain with comparison with the two theories. The obtained analytic solution of the problem is applied for special cases for which the effect of two temperatures is studied. The conductive and dynamical temperatures as well as stress and strain components are shown graphically for a suitable material. Some comparisons are also introduced in the absence and in the presence of gravity, and two-temperature parameter. The differences in the obtained results between the two theories are considered.
12
Content available Interaction of internal and surface waves in a two-layer fluid with free surface
88%
Naradovy V.
Challenges of Modern Technology
|
2013
|
tom Vol. 4, no. 3
3--9
EN
The interaction of internal and surface waves in a two-layer fluid with free surface has been considered. The stability of wave packets propagation on the contact surface and free surface of hydrodynamic system „layer with rigid bottom - layer with free surface” was investigated. The amplitudes of the second harmonics of the elevations of the contact surface and the free surface are investigated.
13
Content available remote Effects of soil layering on the characteristics of basin-edge induced surface waves
88%
Narayan J. , Kumar S.
Acta Geophysica
|
2009
|
tom Vol. 57, no. 2
294-310
EN
This paper presents the effects of soil layering on the characteristics of basin-edge induced surface waves and associated strain and aggravation factor. The simulated results revealed surface wave generation near the basin-edge. The first mode of induced Love wave was obtained in models having increasing velocity with depth and a large impedance contrast between the soil layers. Amplitude amplification or de-amplification of body waves was proportional to the impedance contrast between the soil layers. The average aggravation factor was inversely proportional to the impedance contrast between the soil layers in case of increasingvelocity models and proportional in case of decreasing-velocity basinedge models. On the other hand, the maximum strain was inversely proportional to the impedance contrast between the soil layers in both cases. On the average, strain was greater in case of increasing-velocity models but the average aggravation factor was greater in case of decreasingvelocity models.
14
Content available Dynamics of the FKT system with different mooring lines
88%
Wu J.-T. , Chen J.-H. , Hsin C.-Y. , Chiu F.-C.
Polish Maritime Research
|
2019
|
tom nr 1
20--29
EN
To harness the endless hydrokinetic energy of the Kuroshio current, the joint research team of the National Taiwan University and the National Taiwan Ocean University has developed a floating Kuroshio turbine (FKT) system in Taiwan. In normal operation, the system floats at a certain small depth from the ocean surface to reduce the wave effects and take advantage of faster current speeds. In the present study, the effect of the mooring line on the system dynamics is investigated computationally. Two different auxiliary mooring line designs and, for each design, three different common mooring lines (polyester ropes of neutral buoyancy, iron chains, and 6×19 wires ropes with wire core) are examined. The study makes use of several commercial and in-house packages, integrated to find various coefficients. It is found that the mooring line, the auxiliary mooring line design, and the gravity centre can have a significant effect on system fluctuations in normal operation if the combination of these factors is not properly matched.
15
Content available remote Run-up of dispersive and breaking waves on beaches
88%
Massel S. R. , Pelinovsky E. N.
Oceanologia
|
2001
|
tom No. 43 (1)
61-97
EN
Transformation of waves on sandy beaches, their breaking, set-up and run-up are the main factors contributing to fluctuations in the water table and groundwater flow. In this paper, the run-up mechanisms have been studied using analytical models. In contrast to the standard models, the waves approaching the shoreline are assumed to be dispersive and the equivalence of the non-linear and linear solutions for the extreme characteristics of wave run-up, such as the height of maximum run-up and the velocity of run-up, are used. A linear system of equations for the run-up of breaking waves is developed. This system is based on the application of the mild-slope equation in the deeper area, where waves are dispersive, while the linear equations of shallow water are applied close to the shoreline, where the water depth is a linear function of distance. The dissipation factor in the shallow water equation has been formulated using its resemblance to the mild-slope equation for a non-permeable sea bottom. Application of the method is illustrated for various bottom profiles and wave characteristics, and theoretical results compared well with experimental data. These solutions of the run-up phenomena will assist future studies on wave-induced beach groundwater flow.
16
Content available remote Unexpected properties of SH-waves in superconducting heterostructure
75%
Drzewiecki A. , Maruszewski B. , Starosta R.
Vibrations in Physical Systems
|
2008
|
tom Vol. 23
109--114
EN
The paper provides confrontation of a surface wave of SH polarization propagating in a superconducting layer (type II superconductor) located in a superconducting halfspace of similar material properties. It was found that the wave in the determined heterostructure is distinguished by the properties significantly different from classical Love wave propagating in similar elastic structure. Among more important differences first of all should be mentioned occurrence of only one mode and changed direction of the inequality that determines allowable range of phase velocity of propagating wave. Both waves are subject to normal dispersion.
17
Content available Diffraction of sound pulses on a spherical target in an oceanic waveguide covered with ice
75%
Grigorieva N. , Kupriyanov M. , Ostrovskiy D. , Stepanova D.
Hydroacoustics
|
2016
|
tom Vol. 19
139--144
EN
This paper is devoted to modeling of the pulse scattering by a spherical target immersed in a homogeneous waveguide covered with ice. For calculating the echo signal in the frequency domain we have followed Hackman and Sammelmann’s general approach. The arising scattering coefficients of a sphere were evaluated with the use of the normal mode method. The amount of normal modes forming the backscattered field is determined by the given directivity of the source. The emitted signal is a pulse with a Gaussian envelope. Computational results are obtained in a wide frequency range 8 - 12 kHz for water depths equal to several hundreds of m, and distances between the source/receiver and a target from 1 km up to 10 km. The target is assumed to be acoustically rigid or fluid. In particular, the properties of the ice cover and a scatterer may coincide.
18
Content available Wave propagation in 2D between two elastic media in contact in theory of generalized two-temperature thermoelasticity with gravity effect
75%
Lotfy K. , Gabr M. , Abd El-bary, Alaa , Lotfy K. , Gabr M. , Abd El-bary, Alaa
|
|
nr 1
19
Content available Surface waves in non-homogeneous, general magnetothermo, viscoelastic media of higher order
75%
Sethi M. , Gupta K. C. , Rani M.
International Journal of Applied Mechanics and Engineering
|
2013
|
tom Vol. 18, no. 4
1221--1236
EN
The aim of the present paper is to investigate surface waves in a non-homogeneous, isotropic, visco-elastic solid medium of n-th order including the time rate of strain. The theory of generalised surface waves has firstly been developed and then it has been employed to investigate particular cases of waves, viz., Stoneley, Rayleigh and Love type. The wave velocity equations have been obtained for different cases and are in well agreement with the corresponding classical result, when the effects of viscosity, temperature, magnetism as well as nonhomogeneity of the material medium are ignored.
20
Content available remote Surface waves in a micropolar elastic solid containing voids
75%
Mondal A. , Acharya D.
Acta Geophysica
|
2006
|
tom Vol. 54, no. 4
430-452
EN
The present paper investigates the effect of voids on the propagation of surface waves in a homogeneous micropolar elastic solid medium which contains a distribution of vacuous pores (voids). The general theory for surface wave propaga-tion in micropolar elastic media containing voids has been presented. Particular cases of surface waves (Rayleigh’s, Love’s and Stoneley’s) in micropolar media which contain vacuous pores have been deduced from the above general theory. Discussions have been made in each case to highlight the effect of voids and micropolar character of the material medium separately. Their joint effect has also been studied in details. Modulation of Rayleigh wave velocity has been studied numerically. It is observed that Love waves are not affected by the presence of voids.
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